There seems to be no rhyme or reason for the silver piece, though I do see them more on 996 models.
The inner reflector diffuser also comes in 2 styles (half and full). There is another style with the backside of the lens painted silver around the light openings and there are 2 shades of amber.
...so you actually have at least 8 choices.
I built a set of Litronics with amber lenses, so they are out there somewhere, too (though, not stock).
